To the Editor.—Dr. Miller's comments regarding our report on "Wilms' Tumor and Congenital Heart Disease" were most interesting and stimulating. We believe, however, that at least some of the relationships he mentioned are still within the realm of speculation.
We did report the coexistence of Wilms' tumor and transposition of the great vessels with Ebstein's anomaly, perhaps for the first time. We did not imply, or intend to imply, that a causal, hereditary, or other specific relationship existed between these lesions. We stated that the findings "could be fortuitous and in no way etiologically related." We also mentioned the possibility that genetic factors could have been of etiologic significance.
A single case does not establish anything beyond the existence of a set of facts. It is only by recording and analyzing many cases that a hypothesis may be formulated, tested, and clarified. The purpose of our paper was to